Podoscopic classification of second toe deformities

The AFCP (French Association of Foot Surgery) classification was recently introduced as a reliable and quick visual method for the assessment of sagittal plane deformities of the second toe. The aim of this study was four-fold: (1) to describe a new toe-ground area score (TAS) as an additional dynamic tool of such classification, (2) to verify whether all second toe deformities could be classified, (3) to assess the TAS intra- and inter-observer reliability and (4) to evaluate the TAS learning curve.

In this retrospective study 52 s toes were evaluated using a podoscope. Ten foot and ankle surgeons assessed independently standardised videos of each case acquired in a blinded fashion. Assessment was repeated three times, 15 days apart. Intra- (Intraclass Correlation Coefficient or ICC) and inter-observer reliability (Fleiss' Kappa coefficient) were calculated. Mean time to assess a deformity was also recorded.

All the 522 observations (52 feet assessed by 10 surgeons) were successfully rated using the TAS. Intra- and inter-observer reliability were substantial for the first round (ICC: 0.79; Kappa: 0.76) and excellent for the second (ICC: 0.88; Kappa: 0.8) and third round (ICC: 0.84; Kappa: 0.81). Mean assessment time ± standard deviation was 22 ± 11 s per case for the last two rounds.

The TAS has been proven reliable and quick in the assessment of second toe deformities. When combined with a static segmentary classification of the toe (such as the AFCP classification) it might provide further dynamic informations about the ability of the toe to engage the ground.

Level IV, retrospective cohort study.